1. Field of Invention
The invention relates to an optical mechanism and in particular, to an optical actuator.
2. Related Art
In the present projecting systems, the digital light processing (DLP) projector has the advantages of high brightness, better color appearance, fast response time and no noise. Thus, the DLP projector has been wildly used in theatre, office and family. In order to obtain better images smoothness, the DLP projector has an image smoothing device with an optical actuator fixed at a position on the light path. Therefore, the aligning structure for the optical actuator can critically affect the image quality of the DLP projector.
FIG. 1 shows a conventional aligning structure 13 for an optical actuator 1. The optical actuator 1 includes a main structure 10, a base 11 and an optical element 12. The optical element 12 is a lens or a reflective mirror and is disposed on the base 11, which is connected to the main structure 10. The aligning structure 13 includes a bracket 14 and an adjusting element 15. The main structure 10 is disposed inside the bracket 14. The plate 101 of the main structure 10 has a connecting member 102, which is fixed to the bracket 14. The adjusting element 15 has an elastic member 151 and a locking member 152. The elastic member 151 is a spring, which is not rigid and telescoped to the locking member 152. The locking member 152 is a screw or a bolt.
After the optical actuator 1 is connected with a lens set of the projector (not shown), the adjusting element 15 adjusts the optical element 12 to retrieve an aligning position according to the imaging result. Then, a glue G is applied to fix the connecting member 102. As the result, the optical element 12 can function normally during the oscillation. However, the aligning structure 13 for the optical actuator 1 must be fixed by other glue or assistant objects after the adjustment.
FIG. 2 shows another conventional aligning structure 23 for the optical actuator 2. As shown in FIG. 2, the optical actuator 2 includes a main structure 20, a base 21 and an optical element 22. The optical element 22 is disposed on the base 21, and the base 21 is connected to the main structure 20. The aligning structure 23 includes a bracket 24 and an adjusting element 25. The main structure 20 has a first plate 201 and a second plate 202. The adjusting element 25 has an elastic member 251 and a locking member 252. The first plate 201 is fastened to the bracket 24 by screws S and the adjusting element 25 is connected to the first plate 201. The elastic member 251 is sandwiched between the first plate 201 and second plate 202. The elastic member 251 is a plate with higher rigidness. The locking member 252 is disposed on the bottom of the bracket 24 and pushes against the second plate 202.
In the adjusting procedure, the locking member 252 is adjusted to push against the second plate 202. Thus, the optical element 22 can be adjusted to align with a datum plane P of the bracket 24 so as to finish the adjusting procedure of the optical actuator 2.
However, the elastic member 251, which has higher rigidness, is disposed between the first plate 201 and second plate 202, and the second plate 202 can only be adjusted upwardly, so that utilizing the locking member 252 to push against the second plate 202 is hard to precisely align the optical actuator 2.
Therefore, it is an important subject to provide an aligning structure for an optical actuator that can simplify the aligning procedure for the optical element, enhance the reliability of the aligning structure and simplify the structure of the optical actuator.